" The Neanderthals had it tougher; their long spears and canyon ambushes were useless against the fleet prairie creatures, and the big game they preferred was retreating deeper into the dwindling forests. Well, why didn’t they just adopt the hunting strategy of the Running Men? They were smart and certainly strong enough, but that was the problem; they were too strong. Once temperatures climb above 90 degrees Fahrenheit, a few extra pounds of body weight make a huge difference—so much so that to maintain heat balance, a 160-pound runner would lose nearly three minutes per mile in a marathon against a one hundred-pound runner. In a two-hour pursuit of a deer, the Running Men would leave the Neanderthal competition more than ten miles behind. Smothered in muscle, the Neanderthals followed the mastodons into the dying forest, and oblivion. The new world was made for runners, and running just wasn’t their thing. Privately, "

― Christopher McDougall , Born to Run: A Hidden Tribe, Superathletes, and the Greatest Race the World Has Never Seen